Ahmed Khalfan Ghailani, the first Guantanamo detainee to face a civilian trial, has been acquitted in New York City of all but one charge

Barack Obama's drive to prosecute Guantanamo prisoners in American courts lay in tatters today after the first detainee to face a U.S. civilian trial was found guilty on a single conspiracy charge - but cleared on 284 other counts.

Republicans called for the President to tear up his home trial policy after a New York jury cleared Ahmed Khalfan Ghailani of almost every charge linked to the 1998 African embassy bombings.

The 36-year-old, a Tanzanian from Zanzibar, had been accused of conspiring in the 1998 Al Qaeda bomb attacks on U.S. embassies in Kenya and Tanzania that killed 224 people.

But jurors found him guilty of one relatively minor charge of conspiracy to damage or destroy U.S. property with explosives after deliberating for five days.

The result will come as a huge setback to President Obama's plans for trying terrorism suspects in the United States.

Ghailani's trial was being watched closely as a test of Obama's approach
to handling the 174 terrorism suspects held at Guantanamo Bay,
including Khalid Sheikh Mohammed, the self-professed mastermind of the
9/11 attacks.

It was a rare defeat for the U.S. Attorney's Office in New York, which has a near perfect record in prosecuting terrorism cases.

Obama has vowed to close the US prison at Guantanamo Bay amid international condemnation of the treatment of detainees, but he has run into political resistance at home.

His administration has adopted an approach that favours military tribunals in some cases for terrorism suspects and civilian trials in others.

Ghailani faces a mandatory minimum of 20 years in prison and a maximum
of life even though he was cleared of 276 murder and attempted murder
counts, along with four other conspiracy charges.

Justice Department spokesman Matthew Miller said: 'We respect the jury's verdict and are pleased that Ahmed Ghailani now faces a minimum of 20 years in prison and a potential life sentence for his role in the embassy bombings.'

U.S. Attorney Preet Bharara said he would seek life in prison for Ghailani at his sentencing on January 25.

King, who is in line to chair the House of Representatives Homeland Security Committee when his party takes control of the chamber in January, said last week one of his main prioritieswould be stopping Obama's plans to transfer Guantanamo Bay detainees to the United States to stand trial in civilian courts.

President Obama has backed off an initial proposal to prosecute Mohammed and other accused September 11 plotters in a US criminal court just a few hundred yards from the World Trade Centre site, but has not revealed new prosecution plans.

Prosecutors in the Ghailani case were dealt a blow before the trial started when the judge refused to let a key witness testify, basing his decision on protecting the US Constitution from admitting coerced testimony.

Aftermath: The U.S. embassy bomb in Nairobi collapsed the neighbouring Ufundi House, killing around 140 people

Ghailani is depicted in this file courtroom sketch during his arraignment in New York last year

From the outset, prosecutors said they would not use any statements Ghailani may have made while in CIA custody after his July 2004 arrest in Pakistan, acknowledging those statements were likely 'coerced'.

But the judge said the government would not have been able to find the key witness without those statements.

Prosecutors had said the witness told FBI agents he had sold explosives to Ghailani that were used later in one of the bombings.

Defence lawyers said Ghailani had no idea what the equipment was going to be used for.

The Tanzanian was moved to Guantanamo Bay in late 2006, and transferred to New York in June 2009 to stand civilian trial.

The government accused Ghailani of buying seven gas cylinders used in the bomb and the truck used to transport it.

Prosecutors said Ghailani flew to Pakistan along with senior Al Qaeda operatives on the day before the bombings, and that a blasting cap was found in a cupboard in his room.

Defence lawyers called Ghailani a 'naive boy' who was tricked by Al Qaeda and they denied he took the flight to Karachi.

'This verdict is a reaffirmation that this nation's judicial system is the greatest ever devised,' defence attorney Peter Quijano told reporters outside the courthouse.

US District court Judge Lewis Kaplan told the jury it had shown that 'American justice can be delivered calmly, deliberately and fairly by ordinary people - people who are not beholden to any government, including our own.'